The present disclosure generally relates to the art of tapping conduits, pipes or tube-like workpieces and more particularly to tapping an existing conduit for connection with another conduit. In one embodiment, a tapping tee assembly and method are provided with an improved cap assembly for tapping into an existing plastic conduit (e.g., a gas main or a water main) to establish fluid communication between the plastic conduit and another, secondary conduit without requiring removal of the cap assembly. Though the present disclosure will describe the afore-described embodiment in particular detail, it is to be appreciated that the subject matter described herein has broader applications and may be advantageously employed in related environments and applications.
Polymer and plastic piping has become ubiquitous in many industries and is used within many varying types of pipeline networks (e.g. water pipelines, gas pipelines, etc.). The pipeline network typically includes pipe mains, which are often buried, for conveying the carried fluid (e.g., water or gas) to various locations and service lines, which interconnect a home or business with a selected pipe main. In particular, the pipe main is often an existing or previously installed main that continuously carries a fluid (i.e., a live main), the shutting down of which is highly discouraged and inconvenient. Tapping tees are frequently and advantageously used for connecting secondary conduits, such as service lines, to pipe mains, particularly when the secondary conduit is to be installed to a live main. A tapping tee can incorporate a drill-like or cutting tool with a mounting collar for allowing the tee to be positioned at any desired location along the main.
Typically, the tee is first attached to the main by using a split collar arrangement or, alternately, the tee may be fused to the main. Thereafter, the cutting tool is advanced through the sidewall of the main to open a fluid passage between the main and tapping tee. The tapping tee often includes appropriate structure for more easily and conveniently connecting to the secondary conduit, wherein such connection is often completed prior to tapping the main (i.e., advancing the cuffing tool to establish fluid communication). One advantage of such a tapping tee is that it is not necessary to actually sever the entire main, or otherwise interrupt service provided through the main, in order to interconnect the tee. Rather, the tapping tee requires only that a hole be drilled into the main in order to provide for fluid communication therewith.
One exemplary mechanical tapping tee for use in connecting a service line to a main is disclosed in commonly owned U.S. Pat. No. 4,809,735, which is expressly incorporated herein by reference. In particular, the '735 patent discloses a tapping tee assembly including a surrounding saddle or support assembly that is received around the main conduit. A generally cylindrical body is integrally formed with the support assembly and receives a tapping assembly therein. An internally threaded passage extends through the body and is generally perpendicular to the longitudinal axis of the main line. The cylindrical body includes an exterior threaded region that selectively retains a cap in threaded engagement on the body to close an open, upper end of the passage. The tapping assembly is threadedly received in the internally threaded passage and can be selectively advanced or retracted by an appropriate tool when the cap is removed thereby providing access into the passage to the tapping assembly.
More particularly, the tapping assembly includes a cutter member that, when the cap is removed, can be selectively threadedly advanced through a sidewall of the main conduit, forming an opening as it is rotated through the sidewall. Specifically, a spreading or tapered portion of the cutter member advances through the opening to firmly grip the inner wall of the main conduit when properly positioned in place. An elongated portion of the cutter member remains within the main conduit, generally radially inward of the tapered portion. An upper portion of the tapping assembly is subsequently threadedly retracted from the cutter member to establish fluid communication from the main line, through apertures provided in the cutter member, and to a branch or service line connected to the body. Once access to the tapping assembly is no longer needed and fluid communication with the main conduit has been established, the cap can be replaced on the body to close the upper, open end of the passage. The '735 patent also discloses a second embodiment wherein a two-part cutter is again used, but is modified so that material cut from the sidewall of the main conduit, or coupon as it is generally referred to, is removed from the interior of the main conduit. In most other respects, this modified embodiment works in much the same way to establish a fluid passage from the main conduit to a branch passage or service line.
Another exemplary mechanical tapping tee for use in connecting a service line to a main is disclosed in commonly owned U.S. Pat. No. 5,425,395, which is also expressly incorporated herein by reference. In particular, the '395 patent discloses a tapping tee assembly including a body member having an internal passage that receives a tapping apparatus comprised of a cutter having a cutting edge at one end thereof and a sleeve received over the cutter. Like the '735 patent, the body member includes exterior threads for selectively retaining a cap in threaded engagement on the body member to close an open, upper end of the internal passage. When the cap is removed, the tapping apparatus in the internal passage is accessible for selective advancement or retraction.
In particular, the cutter has external threads which enable the tapping apparatus to be advanced, when the cap is removed, to form an opening in a sidewall of the main about which the body member is secured. A retainer member, such as an o-ring, can be used to hold the sleeve and cutter together, particularly during advancement of the tapping apparatus, and the sleeve can include external threads that grip into the main's sidewall. After forming the sidewall opening and threadedly engaging the sleeve with the sidewall, retraction of the cutter leaves the sleeve in place to secure the tapping apparatus to the main and establish fluid communication therethrough. The external threads of the cutter and sleeve preferably have different thread pitches so that the sleeve advances at a slightly faster rate than the cutter to facilitate sealing engagement between the main and the body member. A one-way drive arrangement is advantageously provided between the sleeve and cutter so that once the sleeve is positioned in the main, the cutter can be removed without altering the location of the sleeve. An o-ring can be provided annularly about and radially spaced from the sleeve to sealingly engage around the opening formed by the cutter through the sidewall of the main. Also like the '735 patent, the cap can be replaced on the body to close the internal passage after access to the tapping apparatus is no longer needed (i.e., after fluid communication with the main is established and the cutter has been retracted).
The mechanical tapping tees of the '735 and '395 patents have been commercially successful and are able to provide a leakproof seal with the mains to which the tapping tees are connected. However, one drawback with these tapping tees is that access to the internally disposed tapping apparatus is only achieved by removing the cap from the body in which the tapping apparatus is disposed. Thus, advancement and retraction of the tapping apparatus and its cutter can only occur while the cap is removed. This may not be desirable in certain applications because the fluid carried by the main may escape through the passage after fluid communication is established with the main and prior to the cap being secured to the body to close and seal the internal passage.